GROUND ZERO ANALYSIS, INC.

1714 {\.lain Street Eseslnn. California 95320-1927 Telephone: (209) 838-9888 Facsimile: (209) 838-9883

REVISED HEALTH RISK ASSESSMENT REPORT

Prepared for

FORMER PURE-ETCH, CO. FACILITY 1031 INDUSTRIAL WAY

SALINAS, CALIFORNIA 93906

Prepared by

ORIGINAL SIGNED BY -~

Jolm P. Lane CA Registered Geologist No. 6795

TABLE OF CONTENTS

EXECUTIVE SUMMARY

1.0 INTRODUCTION .............................................................................................................................................. 1

2.0 SITE BACKGROUND AND PHYSICAL SETTING .................................................................................... 2

2.1 PROPERTY U 2.2 PHYSICALS 2.3 CONTAMINATION I ..............................

2 3 . 2 Sz~bsu~face mrestigalio 2.3.3 Interim Renzediai Actions

3.0 SITE SPECIFIC SUBSURFACE CONDITIONS ........................................................................................... 3.1 PHYSICAL CONDITIONS 3.2 DISTRIBUTION OF RESI

3 2.1 h-tent of Hydrocarbons in S u 3.2.2 Extent ofHydrocarbons in Gr

4.0 HEALTH RISK ASSESSMENT .................................................................................................................... 11

4.1 HUMAN HEALTH SCREENING EVALUATION

4.1.11 Land Use

4.1.1.3 Chemicals of Concern 4.1.1.4 Exposure Point Conce 4.1.1.5 Toxicity Values

4.1.2.1 Selection of Pathways 4.1.2.2 'Water Pathway 4.1.2.3 Soil Pathwa 4.1.2.4 Air Pathway 4.1 2.5 Summation

42 .1 Site Spec$ 4.2.1.1 Land Use

4.2.1 4 Exposure Point Coilce 4.2.1.5 Toxicity Values

4 , 2 2 2 OotdoorAirPathw 4.2.2.3 Indoor Air Pathwa 4.2.2.4 Su~nmation of Ris

5.0 REFERENCES ................................................................................................................................................. 29

TABLE OF CONTENTS (continued)

Physical-Chemico and Toxicity Constants for Human Health Risk Evaluation Cancer Risk Calculatioi~s, Residential Property Use-Maximum Concentrations Toxicity Hazard Calculations, Residential Property Use-Maximum Concentrations Cancer Risk and Toxicity Hazard Calculations, Illdustrial Property Use-Maximum Concentrations

5 : Summary of the Indoor Air Screening Evaluation 6: Proposed Preliminary Remedial Goals (PRGs)

Fieures I : Site Location Map 2: Site Plan 3: Aerial Photomap (Areas of Concern) 4: Site Plan Showing Locations of Borings, Monitoring Wells, and Lines of Section 5 : Stratigraphic Cross Section A-A' 6: Stratigraphic Cross Section B-B' 7: ~otentioietric Surface Map, January 13,2005

Appendices A: Data Summary Tables from Site Characterization B: Contaminant Mass Calculations and Associated Figures C: Risk Screening Evaluation Model Equations ( F ~ ~ ~ P E A Guidance Manual)

HEALTH RISK ASSESSMENT REPORT Former Pure-Etch, Co. Facility

1031 Industrial Way Salinas, California 93901

EXECUTIVE SUMMARY

The purpose of the health risk assessment was to develop a set of health and environmental criteria to which measured andlor predicted concentrations of hazardous constituents determilled during the release characterization could be compared in order to evaluate the need for further site characterization, risk assessment, or corrective measures.

The Site occupies approximately 1.25 acres in an industrial area of Salinas at the southeast corner of industrial Way and Vertin Avenue. Surrounding property use is primarily industrial, with some com~nercial use. The nearest surface water body is Alisal Slough, located more than 2,000 feet southwest of the Site. Drinking water wells in the Salinas area generally draw water from well below 180 feet. The nearest known water supply well is located more than 1,000 feet north (upgradient) of the Site.

Pure-Etch obtained the Site from Georgia Pacific Corporation in 1993 and conducted operations ulitil it was closed in 1998. Pure-Etch did not operate any underground storage tanks (USTs). Prior to Pure-Etch's purchase of the Site, previous owners had legally closed a 1,000-gallon UST in place in 1985 by filling it with concrete. The tank had reportedly not been in use for 10 to 25 years prior to its closure in 1985. The entire Site is now paved. Twenty-five sites within '/4 inile of the Site were listed in a recent VISTA Report as having USTs, including at least five that have a documented release of petroleum hydrocarbons.

Subsurface investigations at the Site conducted since 1997 determined that soil and groundwater beneath the UST has been impacted by a release of petroleum hydrocarbons. Soil contamination at the Site is generally limited to a relatively small area in the vicinity of the UST and lies primarily within the upper claylsilt unit and tlie upper sand unit to a depth of approximately 40-45 feet below ground surface (bgs), although soil contamination is also present within the capillary fringe zone at approximately 55 feet bgs. A11 estimated 27,000 pounds of gasoline remains in soil beneath the site.

The dissolved gasoline plume encompasses an area of approximately 33,000 square feet and the leading edge of the main plume extends approximately 140 to 150 feet downgradient of the source area. The dissolved contaminant plume has partially migrated only 60-65 feet off-site beneath Industrial Street at the southwestern property boundary. An estimated 56 pounds of gasoline is present in the dissolved contaminant plume.

Revised Hmlt11 Risk Assessment Report Former Ptrre-Etclt Facilia, Snlintrs, CA

Ground Zero adopted a tiered approach in conducting the health risk assessment, first conducting a conservatively biased source-based health screening assessment pursuant to DTSC's Preliminary Endangerment Assessment Guidance Manual (PEA) to estimate a reasonable inaxi~num exposure (RME) to a sensitive population, then conducting a receptor-based exposure assessment that evaluates site specific factors in establishing exposure pathways and riskihazard equation parameters.

Although the results of the PEA cornpliant risk screening evaluation suggests that subsurface contamination beneath the Site represent unacceptable riskihazard in a residential setting, it is clear that the risk screening evaluation is a conservatively biased estimate of the upper bound of exposure. Actual site conditions, ilicluding its location, zoning, and the regional hydrogeology of the Salinas area, result in the eliini~latio~l of direct dermal exposure and ingestion of soil or groundwater as exposure pathways. For industrial Site use, site specific risk assessment suggests that, from a receptor-based standpoint, no further action at the site is warranted.

f

However, analytical results of soil samples collected at the site suggests thatlsoil contamination\ remains in the vadose zone, which represents a continuing source of groundwater degradation /

\ via leaching of contaminants to the groundwater andlor contaminant partitioning. In addition, ,

the dissolved hydrocarbon plume is migrating off-site beneath Industrial Street along the southwestern Site boundary. Thus corrective measures and preliminary remediation goals (PRGs) at the site should focus on reducing residual hydrocarbons in soil to prevent continued degradation of shallow groundwater beneath the site and plume migration control to prevent further off-site migration of the dissolved petroleu~n hydrocarbon plume.

Based upon the objectives listed above, Ground Zero initially proposed PRGs for soil using the values established by USEPA Region IX PRGs for industrial Site use. For groundwater, Grouild Zero proposed PRGs that would result in a reduction of the current concentrations of co~istitue~lts of concern in groundwater by about 95%. In a memorandum dated August 2, 2005. which was included with correspondence dated August 5 , 2005, DTSC concurred with Ground Zero's proposed PRGs for contaminants in soil, but disagreed with the proposed PRGs for groundwater. DTSC required that the proposed PRGs for groundwater be equal to the primary Maximum Contaminant Levels (MCLs) established by the State. The revised PRGs for the site are discussed in this Revised I-Iealth Risk Assessme~it Report.

HEALTH RISK ASSESSMENT REPORT Former Pure-Etch, Co. Facility

1031 Industrial Way Salinas, California 93901

1.0 INTRODUCTION

The purpose of the health risk assessment was to develop a set of health and environmental

criteria to which measured andlor predicted concentrations of hazardous constituents determined

during the release characterization could be compared in order to evaluate the need for further

site characterization, risk assessment, or corrective measures. The following general procedures

were used to conduct the health risk assessment:

1. Conduct a human health screehing evaluation pursuant to procedures outlined in the Prelinzinrrry

Endangernzent Assessnzent Guidance Manual (DTSC, 1994). This screening evaluation is

intended to be a health-conservative preliminary evaluation of risk and hazard and mandates the

following:

a) Assumes residential land use;

b) Assumes that inhalation, ingestions, and dermal absorption are all applicable exposure

pathways regardless of actual site conditions;

c) Requires the use of the maximum detected concentration of each specific chemical detected

during the investigation;

d) Establishes default exposure factors that must be used in the calculation of risklhazard. The

default factors are chosen to represent a reasonable maximum exposure in a residential

setting at Superfund sites.

2. Conduct additional risk assessment incorporating site specific factors including:

a) Evaluating actual present and probable future land use;

b) Characterizing the exposure setting;

c) Identifying exposure pathways;

Revisell Health Risk Assessment Report Former Pure-Etclz Facility, Salinirs, CA

d) Establishing exposure parameters based upon land use;

e) Quantifying exposure.

3. Evaluate subsurface vapor intrusion to indoor air pursuant to Interinz Final Guidctnce for the

Evcrluution and Mztigation ofSztb.surface Vapor 1ntvu.rion to Indoor Air (DTSC, 2004).

This report summarizes the procedures and results of the health risk assess~nent coiid~~cted for

the site by Ground Zero.

2.0 SITE BACKGROUND AND PHYSICAL SETTING

2.1 Property Use

The Site is located at 1031 Industrial Way, Salinas, California. The Site occupies approximately

1.25 acres in an industrial area of Salinas at the southeast corner of Industrial Way and Vertin

Avenue. Surrounding property use is commercial and industrial. The nearest surface water body is

Alisal Slough, located more than 2000 feet southwest of the Site. The Site location is shown on

Figure 1.

The Site is currently occupied by Trece Inc., which manufactures insect monitoring products, and an

automobile towing company. The Site was previously operated as an etchant recycling facility by

Pure-Etch from approximately 1994 to 1998. Pure-Etch obtained the property from Georgia Pacific

Corporation in 1993. Prior to Pure-Etch's purchase of the Site, previous owners had legally closed a

1000-gaIIon underground storage tank (UST) in place in 1985 by filling it with concrete. The tank

had reportedly not been in use for 10 to 25 years prior to its closure in 1985. Pure-Etch did not

operate any underground storage tanks. The Site is entirely covered with relatively impermeable

materials, which include concrete slab structures over approximately 80% of the Site and asphalt or

concrete over the remaining 20%. A rail spur enters the southwest portion of the Site from the west.

A site plan is presented on Figure 2.

Reviser1 lfenlflr Risk A s s e s ~ m p f Reporf Furnzer Pure-Etch Facility, Snlinrrs, CA

In 1997 the State of California Department of Toxic Substance Control (DTSC) and the Monterey

County Department of Environmental Health (MCDEH) requested that Pure-Etch undertake an

investigation to determine if any fuel had leaked from the tank.

2.2 Physical Setting

The Site is located in the Salinas Valley, in the central portion of the Coast Ranges physiographic

province of California. The Valley is defined by the Gabilan Range to the east and the Santa Lucia

Range to the west. The Salinas Valley is underlain by the Salinas Ground Water Basin, created by

regional downwarping and localized reverse and strike slip faulting along the eastern range front of

the Santa Lucia Range. This basin is post-Miocene synclinal graben-trough with a repository of

thick mid-late Ce~lozoic sediments up to 8,000 feet thick (Bowen, 1965).

The Salinas Valley Ground Water Basin contains a series of deep productive aquifers, which are

mined intensively to supply water for agricultural, domestic, and industrial purposes. The northern

end of the Valley has two major low permeability confining strata which separate the alluvial fill

into three water bearing units: an unconfined zone, the 180-foot aquifer, and the 400-foot aquifer.

The 180-foot and 400-foot aquifers are highly developed sources of water for irrigation and

domestic use. A deeper, 900-foot aquifer has also been identified regionally. The unconfined zone

yields water slowly, is of poor quality, and is rarely tapped as a water source (Showalter, 1984). The

shallowest aquifer underlying Salinas is the unconfined "A-aquifer." composed of interbedded and

interfingering sands, gravels, silts, and clays. This aquifer is underlain by a relatively continuous

impermeable blue clay layer at approximately 180 feet (California Department of Water Resources,

1973).

Since perched groundwater is present in the shallow, unconfined zone, depth to first groundwater is

variable across the City of Salinas. Regional groundwater flow direction across the Salinas area is

generally west-northwest towards the Pacific Ocean. The shallow aquifer has been encountered at

the Granite Construction Company site (1 161 Abbott Street) in a sand aquifer at a depth of 80 to 100

feet bgs. The Granite Construction Company has monitoring wells less than 1,500 feet southwest of

Revised Henllh Risk A.~sarrmeat Report Former Pure-Etcir Facility, S[~lii~us, CA

the Pure-Etch property (ASE Environmental, December 15, 1993 Remedial Action Plan).

According to Mr. John Goni of the RWQCB, the groilndwater flow direction at the Granite

Construction site has varied considerably and it has been difficult to determine a predominant local

groundwater flow direction.

A nearby water supply well is located at the Shippers Development Company site at 634 South

Sanborn Road less than 1,000 feet north (upgradient) of the Pure-Etch site. The upper perforations of

the water supply well reportedly begin at 235 feet bgs.

On March 9, 2000, VISTA Information Solutions, Inc. conducted a search of regulatory

doculnentation designed to identify sites within one mile of the Site. The search identified 25 sites

within Yi mile of the Site as having USTs. Five of these identified sites, as well as 13 others within

% mile of the Site, are listed as having had leaking USTs (LUSTS). At least two of the LUST sites

are located within 118 mile of the Site. A copy of the VISTA report was presented in the April 12,

2000 Workplan for Investigation ofsoil and Grozrndwater ContaminntionJi-om Former Gasoline

Storage USTat I031 Indus@ial Street, Salinas, California, submitted by Lee & Pierce Inc.

Further review of documents at the MCDEH was conducted on sites identified in the VISTA report.

Significant fuidings include the presence of free-phase petroleum product at the Granite

Construction site (1 161 Abbott Street) approximately 1,000 feet southeast of the Site, and an on-

going investigation for gasoline constituents in groundwater at the Mitchell Silliinan site, located

approximately 113 mile southeast of the Site. Figure 3 presents an aerial photograph showing these

properties in relation to the Site.

2.3 Contamination Investigation, Regulatory Enforcement and Interim Actions

Investigations related to contamination from the UST began at the property in 1997.

2.3.1 Underground Storage Tank Investigations

A previous tenant operated one underground storage tank (UST) on the Site. The steel UST was

Reviser1 fIenit1: Risk Asses.~ment Report Former Pure-Etch Fr~ciiiiy, Salinrrs, CA

used for storage of gasoline fuel. Previous owners of the property closed the tank in place in 1985

by filling it with concrete. The tank was reportedly not used for I0 to 25 years prior to being closed.

2.3.2 Subsurface Investigations

Soil and groundwater investigation was initiated in 1997 at the request of DTSC and MCDEH as a

precursor to plant closure. Three borings were advanced in the vicinity of the closed UST. Two of

the borings located within 10 feet of the UST, BH-1 and BH-2, exhibited elevated levels of gasoline

constituents. Soil vapor samples were collected from each boring at a depth of approximately 15

feet bgs. Each of the three sainples contained gasoline constituents, with the sainple collected from

BH-1 recording the highest level at 18,000 micrograms per liter (~g1L) total petroleum hydrocarbons

as gasoline (TPHg).

Groundwater was not encountered during the 1997 investigation. The drilling was terminated at

approximately 40 feet bgs.

In response to a Corrective Action Consent Agreement (Consent Agreement) between Pure-Etch

and the DTSC signed on February 14, 2000, Pure-Etch authorized an additional investigation in

order to determine the lateral and vertical extent of impact to soil and to determine if there had

been an impact to groundwater. Seven additional soil borings were advanced in July and August

2000 by Ground Zero. Three borings located within 20 feet of the UST (BH-6, BH-8, BH-10)

exhibited elevated levels of gasoline constituents in the vadose zone and at the capillar)~ fringe,

three bor~ngs located east (BH-5) and south (BH-4 and BH-7) of the former UST exhibited

elevated levels of gasoline constituents primarily at the capillary fringe, and one boring north of

the UST (BH-9) exhibited no evidence of gasoline contamination. Soil vapor samples collected

from the boring located nearest the UST from a permeable sand zone at a depth of approxi~nately 16

feet bgs contained coilceiitrations of gasoline constituents five orders of magnitude greater than

those detected in the vapor sample collected fkom the siltlclay unit at 7 feet bgs These results

suggest that the upper claylsilt unit is an effective barrier to upward migration of hydrocarbon vapors

to the atmosphere. Discrete groundwater samples collected from borings BH-4 through BH-9

indicated that the highest concentrations of dissolved gasoline constituents were present in areas

Revised Henltl~ Risk Asse.%sment Report Former Pure-Etch Fncilify, Salinrrs, CA

south and east of the former UST.

At the direction of DTSC, five groundwater monitoring wells (MWI through MW5) were installed

at the Site in June 2002 to characterize hydrology and water quality of shallow groundwater beneath

the site. The investigation confirmed that soil conta~nination at the Site is generally limited to a

relatively small area in the vicinity of the UST and lies primarily within the upper claylsilt unit and

the upper sand unit to a depth of approximately 40-45 feet bgs. Based upon initial groundwater

monitoring data, shallow groundwater beneath the site flows generally in a southeasterly direction.

Free petroleu~n product measuring 1.42 feet thick was present in well MWl, located south of the

UST, and elevated dissolved gasoline constituents were present in well MW4, located southeast of

the UST.

Additional investigation was conducted in order to estimate the lateral extent of documented

dissolved gasoline constituents in shallow groundwater beneath the site, to determine if

previously documented free-phase gasoline had migrated downgradient of well MWl, to obtain

sufficient additional contaminant concentration data in soil gas and physical characteristics of

soil beneath the site to evaluate contaminant migration pathways and the potential exposure to

on-site and nearby workers, and to obtain sufficient information on physical characteristics of

soil and groundwater beneath the site to evaluate potential remediation measures. Ground Zero

directed the installation of six additional groundwater monitoring wells (MW6 through MW1 I),

a soil vapor extraction test well (VWI), and six soil vapor probes (within the annular space of

wells MW6, MW9, and MW11). The additional investigation determined that the downgradient

extent of groundwater contaminatio~i was limited to within site boundaries, as no petroleum

hydrocarbon constituents were detected in downgradient wells MW8, MW9, and MWIO.

Figure 4 presents the locations of soil borings and monitoring wells drilled at the site. Summary

tables of soil, groundwater, and soil vapor samples collected at the site are iricluded in Appendix A

along with a summary of groundwater elevation data. Detailed summaries subsurface investigations

conducted at the site are contained in the following reports:

ReviserlHcaltl~ Risk Assrssnlcnt Report Fornzcr Pure-Etch Facility, Sali~tus, CA

. Undevgrotrnd Slo?-age Tmk Site Investigation Report, prepared,for Pzt~,e-Etch Company, 1031

Indzistrinl Wuy, Salinas, Calforniu 93901, April 1997, prepared by CapRock.

. Phase II RCRA Facility Investigalion, Forn~er Pure Elch Facility, I031 Indz~slrial Way, Salinas,

CA 93906, Febrzravy 16, 2001, prepared by Ground Zero and Lee & Pierce, Inc.

Revised Phase II RCRA F~rcility Inve,r.tigation Repol?, Fovnqer Pure-Elch Facility, 1031

Indzislrial Way, Salinas, CA 93906, July 19, 2002, prepared by Ground Zero.

Phase 111 RCRA Facility Ini~estigation Statzrs Report, Former Pure-Etch Facility, 1031

Indzrstrial Way, Salinas, CA 93906, March 23, 2004, prepared by Ground Zero.

2.3.3 Interin1 Remedial Actions

Well MWl contained more than one foot of free-phase gasoline in the well casing on June 18,

2002. Ground Zero initiated bi-weekly free product monitoring and removal on October 24,

2002. Field technicians hand bailed free product from well MW1 on nine occasions between

October 24, 2002 and October 14, 2003. No measurable free product was present in well MWI

between January 6, 2003 and July 17, 2003. Less than one inch of free product was measured in

the well between August 19, 2003 and October 14, 2003. No free product has been measured in

well MWI since October 14, 2003. A total of approximately 2.15 gallons of productlwater

mixture has been removed from the well. No indications of free-phase gasoline have been

observed in any other site well.

3.0 SITE SPECIFIC SUBSURFACE CONDITIONS

3.1 Physical Conditions

Soil stratigraphy encountered during subsurface investigations can generally be divided into the

following laterally continuous units:

Uuuer clavL~iil unit: extends fiom the ground surface to approximately 14/16 feet bgs and

consists primarily of lean to fat clay with silt (with no coarse material). According to the results

Revised Healtl~ Risk As.ses.sn~erzt Report Farmer Pllre-Etclr Facility, Sulinns, CA

of physical testing conducted by Cooper Testing Laboratory, the upper clay unit has an average

permeability of 9.E-08 cm/sec, an average moisture content of 30%, and an average organic

content of 2.5%.

Upper sand unzt: consists of well to poorly graded sand extending from approxilnately 14116 feet

bgs to 36/44 feet bgs. According to the results of physical testing conducted by Cooper Testing

Laboratory, the upper sand unit has an average permeability of 4.E-03 cm/sec, an average

moisture content of 5.3%, and an average organic content of 0.5%.

Middle clay unit: consists primarily of lean to fat clay with some silt and extends from

approximately 36/44 feet bgs to,approximately 55 feet bgs.

Lower silt zmit: consists of silt with less than 5% sand and generally extends from approximately

55 feet bgs to approximately 61164 feet bgs. This unit appears to be thinner in boring BH-6

compared to other site borings. Poorly graded sand was encountered in the upper portion of this

unit from approximately 55 to 58/59 feet in borings BH-6 and BH-10, but does not appear to be

laterally significant. Wells MW8 through MW11 in the southern and eastern portions of the site

did not contain this lower silt unit. Wells MW8, MW9, and MWI 1 instead transitioned from

clay or silty clay directly to a well graded sand approximately 2-5 feet thick at approxilnately

61/64 feet bgs, which was also encountered in wells MW5 and MW7. No sand or silt was

encountered in this unit in well MWIO.

L m ~ c r clay unit: consists of lean to fat clay and extends from approxilnately 61/64 feet bgs to the

bottom of each well (70-80 feet bgs). Site stratigraphy is graphically represellted in cross section

on Figures 5 and 6.

Petroleu~n hydrocarbon odors within the vadose zone were noted in borings drilled in the immediate

vicinity of the UST, including in borings BHI, BH2, BH3, BH6, BI-18, and BHIO, and during

drilling of wells MWI, MW6, and VW1. Gasoline odors were noted at the capillary fringe in these

Reviserl Het~ItIr Risk A~sessmenf Reporf Fornter P~lre-Etch Fncili[v, Srrlinas, CA

tiorings and also in borings BH4, B115, BH7, and wells MW4 and MW7. No odors were noted

during drilling of borings BH9 or wells MW2, MW3, MW8, MW9, MWIO, or MWI 1.

The static depth to groundwater beneath the site has ranged from 55.7 to 66.4 feet below the tops of

the casings (btoc) in Site wells. Free petroleu~n product was measured in well MWI, with a

~naxi~nuln thickness of approxilnately 1.4 feet when the well was installed in June 2001. No free-

phase petroleu~n product has been detected in well MWI since October 2003. No free-phase

petroleurn product has ever been encountered in any other site well.

The shallow groundwater gradient beneath the site in the vicinity of the UST generally flows

southeast at a gradient between approxilnately 0.006 Wft and 0.012 Wft (-31-60 ftlmile). The

potentiometric surface appears to be somewhat irregular across the site, however, with an apparent

mounding effect beneath the southeastern portion of the site near well MWlO and a groundwater

depression near well MWI 1, which is located inside the warehouse facility. A table of historic

groundwater elevations in Site wells is included in Appendix A. A potentiometric surface map

generated using the January 2005 well monitoring data is depicted on Figure 7.

3.2 Distribution of Residual Petroleum Hydrocarbons in the Subsurface

3.2.1 Exter~t of Hydrocarbons in Soil

Laboratory analyses of soil samples collected from borings near the former tankiexcavation pit have

defined the lateral extent of soil contamination in the vadose zone. Vadose soil contarnination of

significance was identified in BHI, BH2, BH3, BH6, BH8, BHIO, MWI, MW6, and VWI, each of

which was drilled within approximately 25 feet of the UST. Soil samples from peripheral borings

did not contain contaminants in the vadose zone, although BH5 contained high levels and BW4,

MW2, MW4, and MW7 contained low levels of hydrocarbons in soil sa~nples collected from the

capillary friuge zone.

The estimated extent of subsurface contamination is shown on the cross sections of Figures 5 and 6

Reviser1 Het~lilz Ri.~k Assessnteni Report Former Pure-Efch Ft~cilify, Snlinn.~, CA

and in Figures B1 through B6 in Appendix B. Ground Zero has estimated that approximately 24,600

pounds of gasoline (as TPHg) are present in the vadose zone soils between the depths of 12 and 52

feet bgs, and approximately 2,500 pounds of gasoline are present in capillary fringe zone and

saturated soils between the depths of 52 and 65 feet bgs. By contrast, it appears that the majority of

speciated benzene in soil occurs in the capillary fringe and saturated zone. The estimated mass of

benzene in the vadose and capillary fringelsaturated zones are 18.5 pounds and 35.5 pounds,

respectively. A summary of mass calculations and associated figures are included 111 Appendix B.

3.2.2 Extent of Hydrocarbons in Groundwater

Analytical results of groundwater samples collected from Site wells in January 2005 indicated that

dissolved gasoline constituents are present in wells MWI, MW4, MW6, and MW7 within the Site's

boundaries, and at l o w ~ l e v e l s ill off-site wells MW2 and MW5. The wells with greatest impact are /--\

wells MW1 a n d , ~ ~ 6 , kith moderate levels in wells MW2, MW4, and MW7, and very low levels L.1 >../'

in well MW5. No gasoline constituents have been detected in upgradient well MW3, downgradient -- wells MW8, MW9, and MWI 0, or cross gradient well MWl I . - C 4 - Figures B7 and B8 in Appendix B depict the estimated lateral extent of groundwater contamination

as of the Janualy 2005 sampling round. The apparent impacted area measures approximately 33,000

square feet and the leading edge of the main plume extends approximately 140 t o m e e t u

downgradient of the source area. The gasoline plume appears to be migrating off-site to the west

and southwest as indicated by the increasing trend of dissolved co~itami~iants in well MW2.

The volume of impacted groundwater and the mass of dissolved contaminant were estimated by

assuming an affected saturated interval of 15 feet (58-73 ft bgs), a total porosity of 30% and

estimating the areas of various concentration levels. It is estimated that approximately 1 . I million

gallons of groundwater has been affected by dissolved gasoline constitue~lts in the main plume and

that the mass of dissolved gasoline (as TPHg) contained therein is approximately 56 pounds. The

estimated mass of benzene in the dissolved groundwater plume is 4.9 pounds.

Reviser1 Henltlt Risk Assessment Reporf Former Pure-Etcl? Fr~ii l ify, Salinrrs, CA

4.0 HEALTH RISK ASSESSMENT

Ground Zero adopted a tiered approach in conducting the health risk assessment. Pursuant to

DTSC's request Ground Zero followed the procedures outlined in DTSC's Prelilninary

Endangerment Assessment Guidance Manual (PEA), dated January 1994, to conducting an initial

human health screening evaluation. The purpose of the screening evaluation is to provide an

estimate of the potential chronic health hazard from a reasonable maxitnuin exposure (RME) to

contamination at the Site and, conseque~ltly is considered a conservatively biased source-based

assessment assuming reside~itial site use.

Ground Zero also conducted a receptor-based exposure assessment that evaluates site specific

factors in establishing exposure pathways and riskhazard equation parameters.

4.1 Human Health Screening Evaluation

The risuhazard estimates outlined in the PEA screening evaluation are calculated for exposure

pathways most frequently encountered at a residential setting.

According to the PEA guidance manual, the screening evaluation is intended to be a health-

conservative preliminary evaluation of potential risk and hazard using narrowly defined default

exposure factors which must be used in the calculation of risklhazard. Using the default factors, the

screening evaluation quantifies the potential lifetime risk and hazard from site conditions for a

defined set of exposure pathways. Little discretion is allowed on the part of the user in deciding

which models, assumptions, and exposure factors to use.

4.1.1 Screening Evaluation Assumptions and Exposure Factors

The followii~g sections outline the required parameters of the human health screening evaluatio~i

defined by DTSC in the PEA guidance manual.

Revised He(tlt11 Risk Assessntenf Report Fornter Pure-Etcl! F[tcility, Srrlinas, CA

4.1.1.1 Land Use

For purposes of the screening evaluation, the land use of the site is assumed to be residential,

regardless of the current use and zoning of the site.

4.1.1.2 Exposure Pathways and Media of Exposure

The PEA-compliant screening evaluation requires that the following exposure routes and media

of exposure are applicable to residential land use:

Inhalation: airborne dust, volatile organic compounds (VOCs) from soils, VOCs from

using household water;

Ingestion: surface water, groundwater (household use only), and incidental ingestion

of soil;

Dermal Absorption: direct contact with soil, surface water, and groundwater (e.g.,

showering).

4.1.1.3 Chemicals of Concern

As indicated in the PEA guidance manual, total petroleum hydrocarbon (TPH) values are not

useful for the human health screening evaluation. Since the source of the TPH has been

demonstrated to be froin gasoline, the critical components are those that have been detected in

soil and groundwater beneath the site, primarily benzene, toluene, ethylbenzene, and xylenes

(BTEX).

In addition to BTEX constituents, Ground Zero included the probable h u ~ n a ~ i carcinogens 1,2-

dichloroethane (1,2-DCA) and 1,2-dibromoethane (EDB), as well as the suspected occupatio~ial

carcinogen naphthalene, as constituents of concern. Other detected constituents, such as , , ' trimethylbenzenes, were eliminated as constituents of concern because they were not included in ' ' =A databases (such as the Toxicity Criteria Database), and others, such as t-butanol (TBA),

Reviser1 tIertlf11 Risk Assessment Reuorf Forfner Pirre-Etc11 FflciliQ, Salinas, CA

were eliminated because they were detected in less than 5% of so11 and groundwater samples or , at very low levels. .------- 1.

/ Certain chlorinated solvents detected in groundwater samples collected from Site wells, such as

/ 1,l-dichloroethene, trichloroethene (TCE), and tetrachloroethene (PCE), were eliminated as k ...>

constituents of concer~l because they were never used, stored, or handled by Pure-Etch. It should

be noted that neither EDB nor 1,2-DCA were ever used, stored, or handled by Pure-Etch but they

are present in groundwater beneath the Site. It should be noted that the distribution of I,2-DCA

in perimeter wells (upgradient wells MW3 and MWl1 and downgradient well MW5) indicate ,&;. L.?. that I,2-DCA in groundwater beneath the site is due largely to an off-site source. In addition, ?fW-&

EDB was detected in only one of 86 soil samples and only 4 of 64 groundwater samples

collected during the investigation, including groundwater samples collected from upgradient

well MW3. Both chemicals were included as constituents of concern however, because they are

components of leaded gasoline and are considered potential human carcinogens.

The following chemicals were included as constituents of concern for purposes of the health risk

assessment:

Benzene;

Toluene;

Ethylbenzene;

- Xylenes;

1,2-Dichloroethane (I ,ZDCA);

1,2-Dibromoethane (EDB);

Naphthalene.

4.1.1.4 Exposure Point Concentrations

The PEA-compliant screening evaluation requires use of the maximum contaminant value which

was found fi.on1 sampling as the exposure point co~icentration. The maximum soil value from

Revise[/ Heflltl~ Ri.~k Assessment Report Former Pure-Efclt Facilify, Sfllil~flr, CA

sampling was also used for estimating ambient air concentrations, as required by the PEA

guidance manual.

For constituents of concern where the sample data indicate the contaminant concentration is

below the laboratory detection limit, then the value of the laboratory detection li~uit was used as

the exposure point concentration as required by the PEA guidance manual.

4.1.1.5 Toxicity Values

The hierarchy of toxicity values used in the screening evaluation was as follows:

1. Cancer potency factors (SFs) and chronic reference doses (RfDs) available in the CalIEPA

Toxicity Criteria Database;

2. SFs and RfDs from the CallEPA Office of Environmental Health Hazard Assess~nent

(OEHHA) Human Exposztre Based Screening Nztnzbe7,s Developed to Aid Esti~nation of

Cleanup Costs for ContaminatedSoil, November 2004, Janz~ary 2005 Revision;

3. US EPA Integrated Risk Information System (IRIS), as presented in Region IX Preliminary

Reinediation Goals (PRGs), October 2004

/-----

~ - - 1

/ % & p i r e d in the PEA guidance manual, an inhalation reference concentration (RfC) was used, 1 i /i when available, to determine the toxicity value for inhalation pathways. The R E , expressed in , I I

I mglrn', was converted to equivalent RfD values by multiplying the RfC by a ventilation rate of 20 i I

i m3/day and dividing it by an average body weight of 70 kg. Table 1 presents a sumlnary of physico- i i

I

i chemical constants and exposure parameters utilized in the risk assessment. I

4.12 RiskHuzr~rd Clzuructerizntion

For each compound detected at the site Ground Zero utilized the screening evaluation to

calculate an upper bound risk andlor hazard for water, soil, and air pathways for a residential Site

Revised HealfI~ Risk Asre.ssn~efzt Reporf Former Pure-Etclf FaciIiQ, Sf~Iinns, CA

use. The excess lifetime cancer risk (termed "Risk," where "in is the medium of exposure) was

calculated for those compounds considered by the CalIEPA or USEPA to pose a carcinogenic

risli to humans. This value represents the risk, or theoretical probability, of developing cancer

from that chemical upon exposure to that medium under the exposure parameters and toxicity

val~res established for the model. The hazard quotient (termed "hazard," where "in is the

medium of exposure) is calculated for all compounds, carcinogenic as well as non-carcinogenic.

This value is a measure of the non-carcinogenic toxicity of a compound; it is not a probability.

The hazard quotient is the ratio of the estimated dose from exposure to colnpounds i n a medium

to a value that is believed not to produce adverse health effects.

The PEA screening evaluation uses equations for calculating risk and hazard that that have been

simplified by incorporating the default values to achieve a reasonable maximurn estimation of

exposure in a residential setting. The equations for risk and hazard use the same default factors,

except for the averaging time (AT). The AT is 70 years for cancer risk, but is set equal to 6

years for non-carcinogenic hazards. Thus, all non-carcinogenic exposures are estimated for a

child. The simplified equations allow for calculation of risk and hazard by using the exposure

factor and three variables: the chemical-specific toxicity value (SF or RfD), the concentration of

the chemical in the medium (C), and a dermal bioavailability term (Kp or ABS). Excerpts from

the PEA guidance manual that show the equations and default exposure factors are included in

Appendix C.

4.1.2.1 Selection of Pathways

Based upon tlie characterization of soil and groundwater conducted to date, Ground Zero Iias

determined that the available water data adequately characterizes the nature of groundwater

contamination beneath the site and, therefore, PEA-compliant screening evaluation requires that

risldhazard from water, soil, and air be calculated.

4.1.2.2 Water Pathway

The risk and hazard froin the water pathway, assuming residential Site use, were calculated using

Revised flenlflr Risk Asessmerlf Report Forn~er Piirc-Etch Facility, Salinlrs, CA

the equations

and Hazardwat,,

Where:

SFo =

SFi =

Cw =

Kp =

RfDo =

RfDi =

(SF0 x Cw x 0.0149) + (SFi x Cw x 0.0149)

+ (SF0 x Cw x 0.0325 x Kp)

= ((CwlRfDo) x 0.0639) + ((Cwl RfDi) x 0.0639)

+ ((CwIRfDo) x 0.0644 x Kp)

oral cancer potency slope, (mglkg-day) ' inhalation cancer potency slope, (mglkg-day).'

concentration in groundwater, mglL

the chemical specific dermal permeability coefficient from water,

oral reference dose, mglkg-day)

inhalation reference dose, (mgikg-day).

The risk calculated is a sumlnation of ingestion exposure, inhalation of VOCs released from

water used indoors, and dermal exposure for a child and an adult. However, hazard is calculated

only for the first 6 years of childhood. Table 2 summarizes the results of the calculated risk from

all exposure pathways. Table 3 su~n~narizes the results of the calculated hazard from all

exposure pathways.

4.1.2.3 Soil Pathway

The risk and hazard from the soil pathway, assuming residential use at the Site, were calculated

using the equations

Risksoil - - (SF0 x Cs x (I .57 E-6)) + (SF0 x Cs x (1.87 E-5) x ABS)

and I-Iazard,,,~ - - ((CslRfDo) x (1.28 E-5)) + ((Csi R D o ) x (1.28 E-4) x ABS)

Revised Henltlr Risk A.sessment Report Former Pure-Etc11 Facilify, Snlin(rs, CA

Where:

SFo = oral cancer potency slope, (mglkg-day).'

Cs = concentration in soil, ~nglkg

Kp = the chemical specific derinal permeability coefficient from water,

RfDo = oral reference dose, mglkg-day)

ABS = absorption fraction, dimensionless.

The risk calculated is a summation of the incidental soil ingestion exposure for a child and an

adult and the dermal exposure for a child and an adult. However, hazard is calculated only for

the first 6 years of childhood. Table 2 su~n~narizes the results of the calculated risk from all

exposure pathways. Table 3 summarizes the results of the calculated hazard from all exposure

pathways.

4.1.2.4 Air Pathway

The risk and hazard from the air pathway is based on the exposure to volatile emissions for

VOCs generated from contaminated soil. The risk and hazard froin the air pathway, assuming

residential use at the Site, were calculated using the equations

Risk,,, - - SFi xCax0 .149

and Hazardair = (CalRfDi) x 0.0639

Where: I

SFi = inhalation cancer slope factor, (mglkg-day).

RfDi = the inhalation reference dose, ingkg-day 3

Ca = ambient air concentration, mgirn

The ambient air concentration of a co~npound can be estimated from the exposure point soil

concentration using the equations

Revise11 Healt11 Risk Assessmen! Reporf Fnrnzrr P~re-Etch Faci/i@, Salinfrrs, CA

and Ei = ((1.6 E 5) x Di x (IHc/Kd) x ~ i ) i ( ' . l ( ~ i x 0.0231((0.284 + 0.046)(Kd/Hc))

where

Ei = emission rate of contaminant "in over the residential lot during the exposure interval, mgisec

Di = diffusivity in air for compound "in, cm2/sec

Hc = Henry's Law constant, atm-m3/mole

Kd = soil-water partition coefficient, cm3/g

Ci = bulk soil concentration of contaminant "in; (chemical concentration in soil, mg/kg x E-6 kgln~g)

The default exposure factors incorporated into the above equations were modified by CalIEPA

from the VOC emission model recommended by USEPA to coincide more closely with expected

residential conditions in California. Emission rates are calculated over the minimum dimensions

of a residential lot in California, 5,000 square feet. Table 2 summarizes the results of the

calculated risk from all exposure pathways. Table 3 summarizes the results of the calculated

hazard from all exposure pathways.

4.1.2.5 Summation of Risk from PEA Screening Evaluation

For cancer risk, the risks from each carcinogen over all exposure media and for all carcinogens

were summed to obtain the total excess lifetime cancer risk posed by the contaminants at the

Site, assuming residential land use and all exposure pathways are valid. For hazard, the hazard

quotients from each compound over all exposure media and for all chelnicals were summed to

obtain the total hazard index posed by the contaminants at the Site, assuming residential land use

and all exposure pathways are valid.

The PEA guidance manual states "In general, a risk estimation greater than E-6 or a hazard index

Reviser1 fIefllt11 Risk Assessment Report Former Pure-Etch F(lcility, S(~linfls, CA

greater than 1 indicate the presence of contamination which may pose a significant threat to

human health. Exceptions will generally include sites with elevated baclcground concentrations,

sites where other agency criteria are more stringent, and sites with specific circumstances that

allow for a risk management decision to elevate the acceptable screening levels." Using the

parameters established by the PEA guidance manual, the screening evaluation indicates that an

unacceptable cancer risk and toxicity hazard exist at the site for upper bound exposure in a

residential setting. Table 2 summarizes the results of the calculated risk from all exposure

pathways. Table 3 summarizes the results of the calculated hazard from all exposure pathways.

The critical pathway for residential exposure to subsurface contaminants at the site is water

ingestionldermal contact, which resulted in a total pathway risk of 2.4 E-2. Total pathway risk

for soil ingestionldermal contact and inhalation of contaminants volatilized from contaminated

soil were 9.8 E-5 and 8.9 E-6, respectively, which are within USEPA range of acceptable cancer

risk between 1 E-4 and 1 E-6.

Although the screening evaluation pursuant to PEA guidelines suggest that the levels of volatile

organic co~npounds in soil and groundwater beneath the Site represent unacceptable risk and

hazard at the Site for residential use, it should be noted that the PEA guidelines focus on source-

based environmental analysis rather than on receptor-based exposure assessment. In other

words, there is very little room for interpretation of actual exposure pathways based up011 site

conditions and site use.

In a report of OEHHA's Risk Assessment Advisory Co~nmittee (1996) entitled A Review of lhe

California Environmental Protection Agency's Risk Assessnzent Practices, Policies and

Gz~idelines, OEFIHA recog~~ized that screening approaches such as those outlined in the PEA

guidance document use conservative default assumptions to compensate for uncertainties in

parameters and ~nodels and are useful for identifying low-risk situations which do not require

further attention. These screening assessments should be recognized as a conservatively biased

estimate of the upper bound of exposure.

Rcvi.ve1IHen1tI1 Risk Assessmer~t Repurt Former Pure-Etch F(zcility, Salirtrrs, CA

4.2 Site Specific Risk Assessment

For co~nparison with the screening evaluation, Ground Zero conducted a receptor-based

exposure assessment that takes into account the current and probable future use of the Site and

site specific physical characteristics that affect exposure pathways.

4.2.1 Site Spec@ Risk Assessment Assumptions and Exposure Fuctors

The following sections outline the assumptions and exposure factors utilized in conducting a site

specific risk assessment.

4.2.1.1 Land Use

The site specific risk assessment focuses on risk and hazard to current occupants of the Site,

which is in a heavy industrial area. We have also assu~ned that the location of the site in this

heavy industrial area precludes redevelop~nent or future residential use.

4.2.1.2 Exposure Pathways and Media of Exposure

The spectrum of possible exposure pathways at a given site for human receptors includes ingestion

of contaminated soil or groundwater, dermal contact with contaminated soil or groundwater, and

inhalation of vapors. For a given site, one or more of these potential exposure pathways may exist

and others may not.

Exposure pathways for potential human receptors were screened to determine which are potentially

complete pathways and should be evaluated for risk and hazard. Complete exposure pathways may

differ depending upon the property use and potential remediation scenarios. The risk and hazard at

the Site were evaluated based upon the assumption that current conditions will remain unchanged

with regard to Site use.

Dermal Contact or Ingestion of Contaminated Soil

Under the current use of the propem, no worker exposure to contan~inated soil exists because no

bare soil is exposed. The location of the Site within a heavy industrial region precludes

redevelopment for residential use. Consequently, dermal contact andlor ingestion of contaminated

Revised Healt/z Risk Assessment Repor! Former Plrre-Etch Fariliq, Srrlillrrs, CA

soil is not considered a complete exposure pathway.

Dermal Contact or In~estion of Contaminated Groundwater

This exposure pathway was also eliminated from consideration. Shallow groundwater in the Salinas

area is of poor quality due to saltwater intrusion and heavy agricultural use. Water supply wells in

the Salinas area typically are screened well below 180 feet bgs. The depth to groundwater of

approximately 60 feet bgs precludes direct contact by site workers.

Inhalation of Vapors from Contaminated Soil or Groundwater

Although contaminated areas at the Site are located beneath concretelasphalt cover, human exposure

to contaminant vapors is a possibility. The toxic conta~ninants identified at the Site are volatile and

exposure could result from vapor migration through the soil into the breathing zone of onsite

workers. This exposure pathway was considered in detail.

Indoor and Outdoor Vapor Ex~osure

The area of soil contamination is located outside the footprint of the building and, consequently,

only the potential for outdoor air exposure exists from volatilization of contaminants from

subsurface soil. However, the groundwater plume appears to extend beneath a portion of the

building. Consequently, both indoor and outdoor air exposures froin the volatilization of subsurface

contarnination were evaluated.

4.2.1.3 Chemicals of Concern

The followi~~g chemicals were included as constituents of concern for purposes of the health risk

assessment:

Benzene;

Toluene;

Ethylbenzene;

Xylenes;

Revised HeaItIt Risk Assessessmctzf Reporf Fornter Pirre-Etclt F~lciliQ, Snlinns, CA

1,2-Dichloroethane (I,2-DCA);

I ,2-Dibromoethane (EDB);

Naphthalene.

4.2.1.4 Exposure Point Concentrations

In order to allow for a reasonable comparison of the site specific risk assessment to the PEA

derived screening evaluation, the maximum soil value from sampling was used for the exposure

point concentration.

For constituents of concern where the sample data indicate the contaminant concentration is

below the laboratory detection limit, then !4 the value of the laboratory detection limit was used

as the exposure point concentration. This is a departure from the PEA guidelines, which requires

use of the detection limit as the exposure point concentration. However, in this instance the

detection limits for 1,2-DCA and EDB used for the screening evaluation were 6.2 milligrams per

kilogram (mglkg), which is substantially higher than the maximuin concentrations detected for

these constituents of concern because the detection limits were elevated due to interference from

other compounds. The actual maximum detected values for 1,2-DCA and EDB in soil were 0.22

mglkg and 0.056 ingikg, respectively. Therefore, we felt '/z the detection limit (or an exposure

point concentration of 3.1 inglkg) was more than adequate to conservatively estimate the

risWhazard for these compounds.

4.2.1.5 Toxicity Values

The toxicity values used in the site specific risk assessment were the same as those used in the

screening evaluation. Table 1 presents a summary of physico-chemical constants and exposure

parameters utilized in the risk assessment.

4.2.2 Risk/Hazard Characterization

For each compound detected at the site Ground Zero calculated a site specific risk andlor hazard

for the air pathway (inhalation of vapors volatilizing from snbsurface soil and groundwater) for

Reviser1 Healtlt Risk Assessment Report Fornter Pure-Etclt facility, Salinas, CA

an industrial Site use. As written previously, direct dermal contact with andlor ingestion of

impacted soil and groundwater beneath the site were eliminated as exposure pathways due to ihe

nature of the Site.

To calculate the inhalation risklhazard associated with industrial use of the site Ground Zero

utilized the non-simplified equations included in Appendix B of the PEA guidance manual,

modified with the exposure factors appropriate for industrial site use. Since industrial site use

assumes that site workers will not be children the portion ofthe equation that calculates exposure

to a child was not used in the calculation of risldhazard. The equations for risk and hazard use

the same default factors, except for the averaging time (AT). The AT is 70 years for cancer risk,

but is set equal to 25 years for non-carcinogenic toxicity.

4.2.2.1 Selection of Pathways

Under the current use of the property, no worker exposure to contaminated soil exists because no

bare soil is exposed. The location of the Site within a heavy industrial region precludes

redevelopment for residential use. Consequently, dermal contact and/or ingestion of contaminated

soil are not considered complete exposure pathways.

Groundwater in the shallow "perched" aquifer as well as in the 180-foot aquifer in the Salinas area is

of poor quality due to saltwater intrusion and heavy agricultural use. Water supply wells in tlie

Salinas area typically are screened well below 180 feet bgs. The nearest known water supply well is

located approximately 1,000 feet upgradient from the subject site. The depth to groundwater of

approximately 58-60 feet bgs precludes direct contact by site workers. Consequently, direct

exposure or ingestion of contaminated groundwater was also eliminated as an exposure pathway.

Although contaminated areas at the Site are located beneath concretelasphalt cover, human exposure

to contaminant vapors is a possibility. The toxic contaminants identified at tlie Site are volatile and

exposure could result from vapor migration through the soil into the breathing zone of onsite

workers. Therefore, this exposure pathway was considered in detail.

Revised Henltlr Risk Assessmerzi Report Former P~rre-Etch Fiidlify, Snlirzns, CA

4.2.2.2 Outdoor Air Pathway

The risk and hazard from the air pathway is based on the exposure to volatile emissions for

VOCs generated from contaminated soil. The risk and hazard from the air pathway under the

current and probable future use of the Site as industrial use were calculated using the equations

Risk,,, = SFi x Ca x (IR x EF x ED)/(BW x AT x 365 dayslyr)

and Hazard,,, = (llRfDi) x Ca x (IR x EF x ED)I(BW x AT x 365 dayslyr)

Where:

SFi

R D i

Ca

IR

EF

ED

BW

AT

inhalation cancer slope factor, (rnglkg-day).'

the inhalation reference dose, mglkg-day

ambient air concentration, rnglln 3

inhalation rate, 20 m3/day

exposure frequency, 250 dayslyr

exposure duration, 25 years

body weight, 70 kg

averaging time, 70 years for carcinogen and 25 years for non-carcinogen

The ambient air concentration of a compound can be estimated from the exposure point soil

concentration using the equations

and Ei = ((1.6 E 5) x Di x (HclKd) x ~ i ) / ( d ( ~ i x 0.0231((0.284 + 0.046)(Kdmc))

where

Ei = emission rate of contaminant "in over the exposure area during the

ReviserlHel~/fh Risk Assessmenf Reporf Former Pure-Etch F~~cility, Srrlinrrs, CA

exposure interval, lnglsec

Di = diffusivity in air for compound "in, cm2/sec

!-Ic = 1-Tenry's Law constant, atm-111~11nole

Kd = soil-water partition coefficient, cm3/g

ci = bulk soil concentration of contaminant "i";

(chemical concentration in soil, mglkg x E-6 kglmg)

For simplicity in the comparison with the upper bound residential risk calculated by the PEA

co~npliant method discussed in Section 4.1, the emission rates were calcuIated over the ln~nilnum

dimensions of a residential lot in California, 5,000 square feet Table 4 swnmarizes the results of

the calculated risk and hazard from the air pathway in an industrial setting.

422.3 Indoor Air Pathway

The equations above were derived to calculate the risk and hazard from the air pathway at the

Site but is not specific to indoor air. DTSC recommends an approach for evaluation vapor

intrusion into buildings and its subsequent impact on indoor air quality in a document entitled

Interim Final Guidance for the Evaluation and Mitigation of Szrbsz~i@ce Vapor Intrusion to

Indoor Air, December 15, 2004 (Revised February 7, 2005). The guidance document

recommends a step-wise approach for the evaluation of vapor intrusion. For sites with existing

buildings, the following steps apply:

Step I - ldentify the spill(s) or release(s). . Step 2 -Characterize the site.

e Step 3 - Identify the site as one where vapor intrusion into indoor air may represent a

complete exposure pathway (VOCs are detected in the subsurface).

Step 4 -Identify whether an imminent hazard exists from vapor migrating into indoor air.

If none exists,

Step 5 - Perform a screening evaluation using the default vapor attenuation factors

provided in the guidance document. If a potential risk exists, . Step 6 - Collect additional site data.

Revised Healtl~ Risk Assessment Repurt Former Pure-Etch FaciliQ, Snlirmas, CA

. Step 7 - Perform a modeling evaluation using site-specific physical parameters and

building parameters as appropriate. If the calculated risk is still significant, . Step 8 - Prepare an indoor air sampliilg workplan, which includes an assessment of the

utility corridors and the development of a contingency plan for appropriate response

actions. Also, conduct appropriate public outreach with the affected community. . Step 9 - Conduct indoor air sampling. . Step 10 - Evaluate the data to determine if the indoor air concentrations are acceptable.

If they are not, . Step 11 - Mitigate indoor air exposure, implement engineering controls, and remediate

the VOC contamination as appropriate and institute long term monitoring.

Steps 1,2, and 3: For this site, Steps 1 and 2 have been completed and we can conclude that

Step 3 holds true; VOCs have been detected in the subsurface.

Step 4: The identification of an imminent hazard is based on the presence of odors in the

building andlor whether any of the building occupants have reported ally illnesses (headache, eye

irritation, nausea, dizziness, etc.) that may be linked to inhaling hazardous vapors indoors. In

this case neither condition exists, so no imminent hazard exists.

I , ~ ,

\\Step 5)) Ground Zero conducted a preliminary evaluation using the attenuation factors provided .\ in the-guidance document. Ground Zero utilized the provided attenuation factor for existing

commercial buildings, which reflects reasonable worst-case conditions for California for the

contamination of indoor air due to intrusion of vapors migrating from subsurface contamination,

in accordance with the guidance document. The following conditions apply on the use of the

default attenuation factors: soil gas measurements should be used; lnaximum contaminant

concentrations should be used; fractured bedrock or other preferential pathways should not exist

at the site; California toxicity factors should be used; cumulative health effects should be

calculated.

The associated cu~ntilative health risk can be quantified by comparing the calculated indoor air

concentrations with the OEHHA indoor air screening numbers pursuant to SB32 (OEHF-IA,

2004, January 2005 Revision). Table 5 presents a summary of the indoor air screening K' ..

evaluation. Based upon this evaluation, the default parameters result in an acceptable ,yr 7 cumulative health risk and no further evaluation is needed. ,i.Ji);bd-

4.2.2.4 Summation of Risk from Site Specific Risk Assessment

For cancer risk, the risks fro~n all carcinogens were summed to obtain the total excess lifetime

cancer risk posed by the contaminants at the Site, assumin!: its current industrial site use will

remain unchanged. For hazard, the hazard quotients all constituents of concern were summed to

obtain the total hazard index posed by the contaminants at the Site, assuming its current

industrial site use will remain unchanged.

,- The excess cancer risk for the industrial use at the Site was calculated at 2.6 E-6, which is well , !

within the USEPA range of 1 E-4 to 1 E-6. The calculated hazard quotient is well below 1 and, - '

___------%I__-___

therefore poses no toxicity hazard. Table 4 summarizes the results of the calculated risk and

hazard from subsurface contamination.

The indoor air health risk was evaluated using guidance documents recently published by -".

CalIEPA and results indicate that an acceptable cu~nulative health risk exists with regard to

indoor air at the Site (Table 5 ) . . '?_ %.\

Revise11 Henltlt Risk Assessnzenl Report Former Pure-Etch Facility, S a l i ~ t ~ ~ s , CA

4.3 Proposed Site Remediation Goals

Although the results of the PEA compliant risk screening evaluatioil suggests that subsurface

contamination beneath the Site represent unacceptable risklhazard in a residential setting, it is

clear that the risk screening evaluation is a conservatively biased estimate of the upper bound of

exposure. Actual site conditions, including its location, zoning, and the regional hydrogeology

of the Salinas area. result in the elimination of direct dermal exposure and iugestion of soil or

groundwater as exposure pathways.

Reviser1 HeirllIz Risk As,ses.~nrent Report Former Plire-Etcl~ Fc~cilify, Solinns, CA

For industrial Site use, site specific risk assessment suggests that, from a receptor-based

standpoint, no further action a t l u e i s warranted. However, analytical results of soil samples

collected at the site suggests that soil contamination remains in the vadose zone, which

represents a continuing source of groundwater degradation via leaching of contaminants to the

groundwater and/or contaminant partitioning. In addition, analytical results of groundwater

samples collected at the site indicate that the dissolved hydrocarbon plume is migrating off-site

beneath Industrial Street along the southwestern Site boundary. Thus corrective measures and

preliminary remediation goals (PRGs) at the site should focus on the following:

I . Reducing residual hydrocarbons in soil to prevent continued degradation of shallow

groundwater beneath the site;

2. Plume migration control to prevent further off-site migration of the dissolved petroleum

hydrocarbon plume. x. \_ ,~._

Based upon the objectives listed above, Ground Zero initially proposed (Health Risk Assessment ),

I Report, June 24, 2005) the adoption of PRGs for soil and groundwater as summarized in Table 6. i

! .'-I For soil PRGs, Ground Zero adopted the values established by USEPA Region 1X PRGs for 1 , < industrial Site use (EPA, October 2004). For groundwater, Ground Zero proposed PRGs based i upon a 95% reduction of the current concentrations of constituents of concern. If the calculated /

i i +i

PRG for a particular constituent was below the primary Maximum Contaminant Level (MCL) I \> 1 A !

for drinking water, then the proposed PRG was adjusted to the primary MCL, as in the case for i .f xvlenes. For EDB and 1.2-DCA. which were detected in site oerimeter wells in what should be 1 $>

'" 15 considered background concentrations, PRGs were proposed based upon these b : : i~ .I

w~ ; ; , ',, ?, Lv' concentrations. Since no primary MCL has been established for naphthalene, the taste and odor ?': 1 ' v ., p i

threshold was selected as the proposed Site .- ....

In a memorandum dated August 2, 2005, which was included with correspondence dated August

5, 2005, DTSC concurred with Ground Zero's proposed PRGs for contaminants in soil, but

:L "Y8 p ,.a" 28

qb 6- 44 ~., $

I C i

/' k-' -,>i'

I , . ? \ \

Reviser1 Hen/!11 Risk Assessn~ent Report Former Pure-E!cl? Fnci/i@, Snlinns, CA

disagreed with the proposed PRGs for groundwater. DTSC required that the proposed PRGs for

groundwater be equal to the primary MCLs established by the State. The revised PRGs for the

site are shown in Table 6.

5.0 REFERENCES

CapRock, 02/97: Workplan, Underground Storage Tank Investigation, prepared for Pure-Etch Company, 103 1 Industrial Way, Salinas, California 93901, February 1997.

CapRock, 04/97: Underground Storage Tank Site Investigatiorz Report, prepared for Pure-Etch Company, 1031 Industrial Way, Salinas, California 93901, April 1997.

CRWQCB, 01/94: Interim Gztidance for Soil Gas Investigcrlion, California Regional Water Quality Control Board, Los Angeles Region, February 25, 1997

DTSC, 01/94: Prelinzina~y Endangerment Assessment Gzridance Manual, Cal EPA, Department of Toxic Substances Control, January 1994

DTSC, 01/00: Corrective Action Consent Agreenzent for the Pzrre-Etch Company, Cal EPA, ' Department of Toxic Substances Control correspondence, January 3 1,2000

DTSC, 01/03: Advisory - Active Soil Gas Investigations, Cal EPA, Department of Toxic Substances Control and California Regional Water Quality Control Board, Los Angeles Region, January 28,2003

DTSC, 12/04: Interim Final Gzridance for the Evalztation and Mitigation of Subsurfnce Vapor Intrusion to Indoor Ail; Cal EPA, Department of Toxic Substances Control, December 15,2004 (Revised February 7,2005)

EPA, 1 1/86: Test Methods for Evalztating Solid Waste, SW-846, US EPA, November 1986

EPA, 04/88: Szpe$zrnd Exposzrre Assessment Manztal, PB89-135859, US EPA; April, 1988

Revisefl HeuIt11 Risk Assessmenf Reporf Former P~rre-Etclz Fncilig, Snlintr.s, CA

EPA, 10188: G~cidccnce for Condztcting Remedial Investigations and Feasibility Stz~Iies Under CERCLA, OSWER Directive 9355.3-01, EPAl54016-891004, US EPA, October 1988

EPA, 03/89: Risk Asse.s.sment Guidance for Szlperjzcnd 540-1-89-001, U S EPA, March, 1989

EPA, 10104. US EPA Region 9 Prelinzmaiy Remediation goal^ IPRGs) Table, US EPA, October, 2004

GSI, 1998: Gwdcmce Manual for RBCA Tool Kit for Chemical R e l e a ~ e ~ , Groundwater Services, Inc. (GSL), 1998

GZA, 0210 1: Phase II RCRA Facility Investigation, Fornzer Pztre-Etch Facility, 1031 Indzcstrial W q , Salinas, CA 93906, Febrzcaiy 16, 2001, prepared by Ground Zero Analysis, Inc. (GZA) with Lee & Pierce, Inc. (L&P)

GZA, 01102: Revised Addendum to Workplan for Investigation of Soil and Groundwater Contamination fvom Fornzer Gasoline Storage UST, 1031 Indz~strial W q , Salinas, CA 93906, prepared by Ground Zero Analysis, Inc., January 30, 2002

GZA, 07102: Revised Phase II RCRA Facility Investigation Report, 1031 Indzcstrial W q , Salinas, CA 93906, prepared by Ground Zero Analysis, Inc., July 17,2002

GZA, 05/03: Gsoundwater Sampling and AnaEysis Plan, UST Contanzination Investigation, Former Pure-Etch Conzpany Site, 1031 Industrial Way, Scilinas, CA 93906, prepared by Ground Zero Analysis, Inc., May 15,2003

GZA, 05/03: Phase III RCRA Facility Invesligation Worhplan, Former Pure-Etch, Co. Facility, 1031 Industrial Way, Salinas, CA 93906, prepared by Ground Zero Analysis, Inc., May 15,2003

GZA, 05103: Site Safety and Health Plan, Pul-+Etch, Co~npaizy, 1031 Indz~stnal Street, Salinas, California, prepared by Ground Zero Analysis, Inc., May 2003

GZA, 06105: Health Rlsk Assessment Report, Former Pure-Etch Co Facrllly, 1031 Indz~.\ti~ial Way, Salinas, California, prepared by Ground Zero Analysis, Inc., June 24,2005

L&P, 04100: Wor4qdan for Investigation of Soil and G~*ound~vater Contanzinalion ?on7 Fornler Gasoline Storage UST, 1031 Indz[strial Street, Salinas, CA 93906, April 12, 2000

Revised Herrlt17 Rirh Assessment Report Former Pnre-Etch FnciliQ, Snlinw CA

OEHHA, 1 1/04: Hzmzan-Exposure-Based Screening Nz~nzmlbers Developed to Aid Estinmtion of Cleanzp Costs for Contaminated Soil, CalIEPA, Integrated Risk Assessment Section, Office of Environmental Health Hazard Assessment, November 2004 (January 2005 Revision)

Showalter, P., : Design of a Gmotdwater-Qzmlily Monitoring Nelwork for the Sc~linas Akers, J.P., River Basin, California: US. Geological Sz~wey Wuter-Kesource.~ and Swain, L.A. Investigntions Report 83-4049, 74p., 1984

TABLE I PHYSIO-CHEMICAL AND TOXICITY CONSTANTS

FOR HUMAN HEALTH RISK EVALUATION FORMER PURE-ETCH FACILITY, SALINAS, CA

Notes: physical siaie alchemical at ambient candilions (v- voiatile. Nv- nonuolatiie, S - solid. L - liq~lid, G - gar). c~~omica~ considered to be 'votaiile" if ~enry ' r number (elm m3lmoie) >0.00001 and molecular weiglhl <200. physic-chemical constanls and A ~ S values from UTSC Preliminary ~ndangeiment ~~ ress rnen t ~uidance ~anua l , ~anuary 1994.

Cancer Slope Factors and Reference Uorer from OEHHA Human Expasure Based Screening Numbers Developed to Aid Eslimaliai~ or Cleanup Costs for C~ntaminaled Soil. January 2005, where available (marked by """1: olhewise from USEPA as aresenled in Reaion iX PRGs (USEPA 20041.

OTHER INPUST PARAMETERS-INDUSTRIAL SETTING BW (Adult Body Weight) in Kg ATc (averaging Time for Carcinogens). years

A tnc (averaging Time for Noncarcinogens), years

EFi (exposure frequency ingestion), days i yea r

ED (exposure duration), years

I R w ( intake rate water), U d a y

ET (exposure t ime dur ing showeringlbathing), lhriday

S A s (skin surface area avai lable for soi l contact), sq. cm i R s ( intake rate soil), mq idav

CHEMICAL PARAMETER

'BENZENE

UIBROMOETI-IANE, 1.2- (EDBI 'DICHLOROETHANE, 1.2- 'ETIIYLBENZENE 'NAPIITHALENE

'TOLUENE 'XYLENES

~ ~ c ( e x p o s u r e f requency de rma l contact) day lyr

AF (soil to skin adherance factor) m q i s q c m

Molecular weight

78 188 89

108 128 92 108

iRa (inhalat ion rate), c. me te r lday

- Pi~ysicai

state

organic c s r b o ~ ~pnrtitlon

coclllcicnt.

KO. ,G,,, 31ql

050Ei01 2.81EiOl 1.40Ei01

220E+O2 129Ei03 257E102 240Et02

V -

V

V V V V

L

V l L L S L L

D i l l ~~s iu i~y 181 air,

D. ( ~ r n ~ f s )

880E-02 730E-02 910E-02 - 750E-02 890E~O2 780E-02 870E-02

Pure

cornpoa~ent water

soiubllily,

s ian~IL1

1.78Et03

340Et03 8.52Ei03 IGlE+O2 317E101

2.57Ei02 240Ei02

I I ~ r ~ r y ' s Lawconrtarlt

I 4

(at~n-,o'~mo~l 543E-03 320E~04 877E-04 - 844E-03

5.0OE-04 594E~03 530E-03 -

shin ~bsor i> l ion

Factor

ABS itlnillers)

010 0.10 0.10

0.10 0.10 0.10 0 10

cancer

Slope actor Oral

CSFo

10E-01

36Ei00 47E~02 - 12E-01

cancer

Slope Factor I8811aled

CSFl

imqikq-dj.' l.OE~O1 25E~01 73E~02

1.2E-01

~elerence oose Oral

RlUo

imgihg-dl 30E-03 9.OE-03

3.OE-02 1.OE-01 2.0E-02 20E-01 2 OE-01

~crerencc oose

Inllnled

RfDi

(nlgikg-dl

1.7E-02 28E~03 14E~03 57E-01 26E-03

88E-02 2.OE-01

~ererence Concen!ril~lon

In air

Ca

(rnqirn') 97E-05 92E-05 26E-04

39E-03 7.lE~05 33E-03 18E~02

TABLE 2 Cancer Risk Calculations

Residential Property Use - Maximum Concentrations Former Pure-Etch Facility, Salinas, CA

CANCER RlSK - WATER INGESTION AND DERMAL CONTACT COMPOUND : SFo (mglkg-day).' I SFi (mglkg-day)' I Cw (mgli) I Kp Risk (lifetime excess cancer) Benzene I 1.OE-01 / TOE-01 1 6.8 2 1 E - 0 2 2.07E-02 1.2-dichioroethane i 4.7E-02 / 7.3E-02 ! 0.14 I 5.3E-03 2.51 E-04 Ethylene dibromide 1 3.6E+00 2.5E-01 1 0.044 1 3.3E-03 2.54E-03 Naphthalene I 12E-01 I 12E-01 ! 0.089 1 6.9E-02 342E-04 TOTAL PATHWAY RISK 2.39E-02

CANCER RlSK - SOIL INGESTION AND DERMAL CONTACT COMPOUND : SF0 (mglkg-day).' I Cs (mglkg) ABS (fraction) ! Risk (lifetime excess cancer)

Benzene I 1.OE-01 I 27 0.10 I 929E-06 1,2-dichloroethane : 4.7E-02 1 6.2 I 0.10 : 1.00E-06 Ethylene dibiomide i 3.6E+00 1 6.2 1 0.10 768E-05 Naphthalene i 1.2E-01 ! 27 1 0.10 I 1.11E-05

TOTAL PATHWAY RISK I I l 9.82E-05

CANCER RlSK - INHALATION COMPOUND Ca (mglm') i SFi (mgikg-day).' i Risk (lifetime excess cancer)

9.73E-05 1 10E-01 I Benzene 1.45E-06 1.2-dichloroethane 2.55E-04 7.3E-02 : 278E-06 Ethyiene dibromide 9.15E-05 I 2.5E-01 I 341E-06 Naphthalene 714E-05 1 1.2E-01 1.28E-06 TOTAL PATHWAY RISK 8.91 E-06

TOTAL CANCER RISK ALL PATHWAYS 2.4@~-02

NOTES: Risk calculated using equations and default exDosure factors mandated in PEA Guidance Manual, 1094

TABLE 3 Hazard Calculations

Residential Property Use - Maximum Concentrations Former Pure-Etch Facility. Salinas, CA

TOXICITY HAZARD - SOIL INGESTION AND DERMAL CONTACT

COMPOUND i RiDo (rngikg-day).' ! Cs (rngikg) A B S (fraction) i Hazard Quotient

Benzene 30E-03 l 27 0.10 i 230E-01

Toluene 2 OE-01 I 150 010 i Ethylbenzene 1 OE-01 140 010 1 3 58E-02

ylenes 2.OE-01 810 010 i O4E-01

30E-02 6.2 010 ! 5.29E-03

90E-03 ! 6.2 010 l 176E-02

TOXICITY HAZARD - INHALATION COMPOUND RiDi (rngikg-day).' Ca (mgirns) Hazard Quotient

Benzene 1.7E-02 I 973E-05 I 364E-03

Toiuene 86E-02 1 3.27E-03 i 2.44~-02

Ethylbenzene 57E-01 3.86E-03 ! 432E-03

Xylenes 20E-01 i 1.82E-02 ! 582E-02

1.2-dichloroethane 14E-03 255E-04 116E-01

Ethylene dibromide 2.6E-03 1 9.i5E-05 2.25502

Naphthalene 2.6E-03 714E-05 1.78E-02

TOTAL PATHWAY HAZARD INDEX 2.47E-01

NOTES: Hazard calculated using equations and default exposure factors mandated in PEA Guidance Manual, 1994

TABLE 4 Cancer Risk and Toxicity Hazard Calculations

lndustriallCommerciaI Property Use - Maximum Concentrations Former Pure-Etch Facility, Salinas, CA

NOTES: Pathways for soil and water exposures through ingestion or dermal contact were determined to be incomplete exposure pathways.

CANCER RlSK - INHALATION COMPOUND Ca (mgim') I SFi (mgikg-day).' I i Risk (iifetime excess cancer)

Benzene 9.73E-05 I 1.OE-01 1 1 6.8E-07 1.2-dichloroethane . 128E-04 / 7.3E-02 1 6.5E-07 Ethylene dibromide I 4.58E-05 I 2.5E-01 1 1 8.OE-07 Naphthalene ! 7.14~-05 I 1 .2~-01 I 6 .0~-07 TOTAL PATHWAY RISK 2.7E-06

TOXICITY HAZARD - INHALATION

COMPOUND I Ca (rng/m3) I RfDi (rngikg-day).' 1 I Hazard Quotient

Benzene 1 9.73E-05 I 1.7E-02 1 1 l l E - 0 3

I ! Toluene ! 3.27E-03 1 8.6E-02 7.5E-03

3.86E-03 5.7E-01 1 Ethylbenzene Xylenes 1.82E-02 / 2.OE-01

1.2-dichioroethane 255E-04 / 1.3E-04 1

1.3E-03

1 1.8E-02

1.8E-02

Ethylene dibrornide 915E-05 1 46E-05 1 i 3.4E-03

Naphthalene 714E-05 / 26E-03 / 1 5.4E-03

TOTAL PATHWAY HAZARD INDEX 5.4E-02

TABLE 5 SUMMARY OF INDOOR AIR SCREENING EVALUATION

Former Pure-Etch Facility, Salinas, CA

NOTES: Indoor air screening evaluation conducted pursuant to interim Final Guidance for the Evaiuatioo and Mitigation of Subsurface Vapor intrusion to indoor Air, CaiiEPA DISC, December 15, 2004 (Revised February 7, 2005)

TABLE 6 PROPOSED PRELIMINARY REMEDIAL GOALS

Former Pure-Etch Facility, Salinas, CA

Not considered a completed exposure pathway for industrial Site use.

1,2-dichloroethane

NOTES:

Site specific risk assessment determined that only VOC inhalation air pathway is compiete for industrial Site use

' = Proposed soil PRGs are adopted from USEPA Region IX PRGs established for industrial Site use.

= Initial proposed groundwater PRGs for BTEX constituents were selected based upon 95% reduction in current groundwater contamination or IOOX the current drinking water MCL. whichever was less, Initial proposed groundwater PRGs for EDB and 1.2-DCA reflected maximum background concentrations, based upon detected concentrations in upgradient and downgradient wells not impacted by gasoline constituents. Since no MCLs have been established for Naphthalene in groundwater, the Taste and Odor Threshold was selected as the initial proposed PRG.

= DTSC requires that groundwater PRGs be reduced to the levels of their corresponding MCLs

LAP FILE: 99759-02.dgn 7

LOCATION MAP PURE ETCH

SALINAS, CALIFORNIA

LEE G PIERCE, inc. consulting ~ n g i n ~ ~ r s 546 ABBOTT ST. SUITE 20

SALiNA? CA 93901

JOB No. 99759

DATE: 04-12-00

BY: DP

SHT NO

@CROP IMAGE, 1999

600'

1" ; 600,-0" L6P FILE: 99759-03.dgn

AERIAL PHOTOMAP LEE & PIERCE, inc. JoB No. 00759 SHT Nc

PURE ETCH consuitlng 546 ABBOTT ST., EnglnEErs SUITE 2 0 DATE: 04-13-00

SALINAS, CALIFORNIA SALINAS, CA 9 3 9 0 1 BY: DP

FIGURE 3

LEGEND: E X I S T I N G GROUNDWATER MWICf MONITORING W E L L

V E W y E X I S T I N G V A P O R E X T R A C T I O N T E S T W E L L

BH10. BORING L O C A T I O N